The present invention relates to a handtruck for carrying a load put on the handtruck by hand, in particular, a handtruck for carrying a load in which wheels are installed on the handtruck in order to facilitate transportation of the load.
Conventionally, a handtruck is provided with a rack or frame for receiving the load, a handle for manipulating the handtruck, and a back plate. Bearings are fixedly mounted on the frame. A wheel axle is rotatably carried by the bearings and wheels are installed at both sides of the wheel axle. The handtruck, having wheels installed in such a way, can be easily conveyed, in the case of conveying the same straight on a flat floor. However, since the wheels are so constructed that they cannot rotate around an axis normal to the wheel axle, it is not easy to change the direction of the handtruck. And further, the wheels are not installed so as to be able to move up and down in relation to the frame.
In order to facilitate directional change of the handtruck, a device has been utilized in which a rotatable shaft capable of rotating around an axis normal to the floor surface is mounted on bearings, and wheels are installed on a shaft which is unitarily formed together with the rotatable shaft. In such a construction, the wheels can rotate around the shaft and, at the same time, can rotate together with the rotatable shaft. In such a way, directional change of the wheels can be easily achieved.
However, although the direction of the handtruck having such wheels can be easily changed, the wheels do not move up and down in relation to the frame. Therefore, when the handtruck is moved on an uneven surface, for instance, on a stairs, the movement of the wheels is directly transmitted to the frame of the handtruck, and thereby the load on the handtruck is moved and falls onto the floor or the stairs. It was a problem requiring a solution.